A steel pad supporting heavy machinery rests on four short, hollow, cast iron piers (see figure). The

Question:

A steel pad supporting heavy machinery rests on four short, hollow, cast iron piers (see figure). The ultimate strength of the cast iron in compression is 50 ksi. The outer diameter of the piers is d = 4.5 in. and the wall thickness is t = 0.40 in.
Using a factor of safety of 3.5 with respect to the ultimate strength, determine the total load P that may be supported by the pad.